Preparation of zein nanoparticles and study of its analytical and environmental applications

Dissertation for Master's Degree in Analytical Chemistry

Fluoride has been known as a toxic ion for many years. The main source of fluoride in aqueous solutions is minerals containing fluoride and the industrial activities of factories. According to the report of the Environmental Protection Organization, the amount of fluoride more than 1 mg/liter causes various diseases. In this research, a biopolymer called zein has been used as an absorbent to remove fluoride from water, and the method used to determine the concentration of fluoride in aqueous solutions is the spadence method. Parameters affecting the reaction such as pH, amount of adsorbent, contact time of adsorbent and initial concentration of fluoride have been optimized by the central compound design method. The results showed that the maximum amount of absorption occurs at pH 4.5-6 and within 30 minutes. The ability of the adsorbent to remove fluoride was investigated using the Langmuir and Freundlich isotherms, and the amount of removal per unit weight (1 gram) was found to be 1.2 mg. The effect of other anions on fluoride removal has also been investigated in this research. In another part of this research, zein nanoparticles have been used to prepare carbon paste electrodes for fluoride ions. The effect of other ions on the performance of this electrode has been investigated and the selectivity coefficient of this electrode has also been determined. The results show that the proposed electrode has Nernst behavior in the linear range of 2x10-5-2x10-2 M at a temperature of 25?C, in addition, the performance of this electrode is satisfactory in an acceptable range of our pH between 4-8.  Easy preparation, good selectivity, fast response and long life are unique features of this proposed electrode. 

1-1- Zein

Zein is a fibrous polymer and protein that has a small amount of acidic and basic amino acids, but is rich in amides, leucine, proline and alanine [1]. This protein is found in corn spores, commercially extracted from corn gluten by alcohol and is a byproduct of the bioethanol industry. Zein particles in the diameter range of about 1-2 micrometers are called the main proteins of corn spores. Three distinct components of zein including ?, ? and ? zein can be identified by their different solubility in alcohol solutions. Commercial zein is a mixture of proteins with different molecular mass, solubility and charges. Generally, zein is extracted with hot alcohol solutions and precipitated with cold water, commercial zein also contains ? zein [2].  A mixture of three alcohols ethanol, methanol and isopropanol with the right amount of water is used to dissolve zein, the supercritical antisolvent process is used for the synthesis of micro and nano particles of zein for bioactive compound systems [3]. A structure with ?-9hexyl has been proposed by Argos[1] and his colleagues based on the ability of hydration, polarity and secondary structure.  Commercial zein has a high concentration of ?-hexyl structure in alcoholic water solution. Tima Sheff's research [2] shows that most solvents, such as ethanol, can increase the structure of ?-hexyl zein [2].

Due to the hydrophobic properties of zein, many efforts have been made recently to prepare zein beads and hydrogels, which allows the network structure to remain [3].

1-1-1-Uses of zein

Due to its insolubility in water, zein is a suitable candidate for use in drug delivery systems. A number of proteins are used as barriers or carriers of food components, drugs, and food supplements, and this is due to their biodegradability, low toxicity, and proper absorption and eating ability. Among the proteins, zein can be formed into a film as a result of chemical modification or physical softening or processes like this [1].

Zein film can be prepared simply by evaporating the solvent from Zein solution due to its properties such as stiffness, glossiness, hydrophobicity, resistance to the passage of fat and resistance to microbial attack. These physical characteristics of decorative film have made it used as a coating in food and pharmaceutical packaging. Zein is used to produce microsome proteins for capsule medicines, insecticides, for example, in the food industry, zein is used to create a coating on nuts and sweets to prevent moisture evaporation. Previous research shows that the characteristics of the fine-grained surface have a special effect on loading and combining with active compounds [3]. Biodegradable polymers from renewable sources have attracted a lot of attention due to their positive impact on the economy and the environment. Since oil resources are running out, there is a need for new energy sources, for this reason, more attention has been drawn to the conversion of biomaterials into useful products [3]. rtl;"> Various definitions of nanotechnology have been provided, the National Institute for Pioneering Nanotechnology in America provides the following definition: the development of research and technology at the atomic, molecular and macromolecular levels with an approximate length of 1 to 100 nanometers, in order to provide a basic knowledge of phenomena and materials at the nanoscale and to create and use structures, parts and systems that have new properties and functions due to their small or medium size [4].

Nanoparticles have been used for a long time, during the last few years, the applications of nanoparticles separately and independently of nanotechnology technology have made significant progress and are considered as one of the main aspects of this technology. These advances are in the fields of biomedicine, pharmaceuticals and drug delivery, cosmetics, composites and coatings, etc. and includes the use of inorganic nanoparticles as antibacterial agents in bandages, labels to diagnose diseases, drug carriers, bone materials, biomagnetic separation equipment, etc. is Also, in recent years, progress has been made in the field of the possibility of making and controlling the size, composition and uniformity of nanoparticles. The diversity in the types of nanoparticles is related to the diversity in its applications, as in addition to the mentioned cases, nanoparticles have very wide applications in human life as well as industry. are [5].

2-2-Nanoparticle production methods-1

There are many different methods to produce nanoparticles, which include:

Vapor condensation

Chemical synthesis

Solid state (microscopic) processes

Use of supercritical fluids as a medium for nanoparticle growth

Use of microwave and ultrasonic waves

Using bacteria that can produce magnetic nanoparticles.

After producing nanoparticles, according to the type of their application, common land methods such as coating or chemical modification can also be used.

Steam condensation: This method is used to produce metal ceramic and metal oxide nanoparticles. This method includes the evaporation of a metal and then its rapid condensation, during which the nanometer clusters are deposited in the form of powder. One thing that should be noted is that oxygen is used to prepare metal nanoparticles to prevent oxidation from inert gases and to prepare metal oxide ceramic nanoparticles. Finally, the particle size is controlled by changing parameters such as temperature, evaporation rate and environment. The most important advantage of this method is the low level of contamination and the preparation of transparent metal oxides that are resistant to scratches and defects and its cost. Another type is the vacuum evaporation method on liquid liquids